NCP1871 Narrow Voltage DC Battery Charger The NCP1871 is a NVDC switching battery charger designed for 2−3−4 battery cell applications such as ultra books or tablets. It is optimized for use with the mobile computing chipsets, and is also compatible with most mobile solutions. The NCP1871 is designed around a full NMOS DC to DC controller that brings down the high voltage charger adapter voltage to a regulated system supply that is in the same range as the battery pack voltage. This limits the variation on the system supply voltage, and improves the efficiency of the core converters. The device includes a voltage droop monitor, charger adapter validation and blocking as well as an intelligent battery connection control. The adapter current, charge current and system current are closely monitored and an image is provided to the host. The NCP1871 is fully programmable through an I2C friendly SMBus Interface. www.onsemi.com 1 QFN20 MN SUFFIX CASE 485CP MARKING DIAGRAM XXXXX XXXXX ALYWG G Features • • • • XXXXX A L Y W G = Specific Device Code = Assembly Location = Wafer Lot = Year = Work Week = Pb−Free Package (Note: Microdot may be in either location) PIN CONFIGURATION ACSN HSDRV SW CBOOT VCORE • • • SMBus Host−controlled NVDC−1 2S−4S Battery Charge Controller Instant−on Works with No Battery or Deeply Discharged Battery Automatic Supplement Mode with BATFET Control Battery Removal Sensor Programmable Switching Frequency SMBUS Clock up to 400 kHz (I2C compatible) Programmable Charge Current, Charge Voltage, Input Current Limit with Interrupt Management ♦ ±0.5% Charge Voltage Regulation up to 18.08 V ♦ ±3% Input/Charge Current Regulation up to 8.064 A Support Battery LEARN Function Support Shipping Mode and Hard System Reset Ultra−Low Quiescent Current of 10 mA at OFF Mode and High PFM Light Load Efficiency 80% at 20 mA Load to Meet Energy Star and ErP Lot6 Full NMOS Solution Current and Power Monitoring 3.5 mm x 3.5 mm QFN−20 Package These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant ACSP RBDRV VIN VSEL VINOK 1 20 19 18 17 16 15 2 14 GND 3 13 4 12 5 6 7 8 9 11 10 LSDRV BCSP BCSN BATDRV VBAT PRHOTB PMO SDA SCL TS • • • • • • • (Top View) Typical Applications • Ultrabook • Notebook • Tablet PC ORDERING INFORMATION Device NCP1871MNTXG Package Shipping† QFN20 (Pb−Free) 3000 / Tape & Reel †For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specification Brochure, BRD8011/D. © Semiconductor Components Industries, LLC, 2016 June, 2016 − Rev. 0 1 Publication Order Number: NCP1871/D NCP1871 AC ADAPTOR RIN QAC QRB QLS RAC QHS DF CBOOT LX COUT1 COUT2 SYSTEM LOAD CAC CIN RCELL VIN VDD RBDRV ACSP ACSN HSDRV SW CBOOT LSDRV BCSP VSEL RBC 10k BCSN BATDRV NCP1871 SCL QBAT VBAT RTS PRHOTB PMO TS RPMO VCORE GND CCORE Figure 1. Typical Application Circuit www.onsemi.com 2 RUP VINOK SDA HOST CBAT BATTERY PACK +5V ACSN HSDRV SW CBOOT VCORE NCP1871 1 20 19 18 17 16 15 2 14 GND 3 13 12 4 5 6 7 8 9 11 10 LSDRV BCSP BCSN BATDRV VBAT PRHOTB PMO SDA SCL TS ACSP RBDRV VIN VSEL VINOK Figure 2. Pin Out Description (Top View) Table 1. PIN FUNCTIONAL DESCRIPTION Pin Name Type Description 1 ACSP ANALOG INPUT 2 RBDRV ANALOG OUTPUT 3 VIN ANALOG INPUT Charger Adapter Input. Bypass with a Damping network 4 VSEL ANALOG INPUT Adapter detection input. Program adapter valid input threshold by connecting a resistor divider from adapter input to VSEL pin to GND pin. Connect a serial resistance of 220 kW to select 3−4 Cells default setting. 5 VINOK OPEN DRAIN OUTPUT Charge Adapter Valid Output. Signals the VIN is within the target range. Open drain output requiring an external pull up. Also use for short pulse signal interrupt generation 6 PRHOTB OPEN DRAIN OUTPUT Processor Hot Signal Output. Pulled low to reduce processor speed based on BCSP. 7 PMO ANALOG OUTPUT 8 SDA DIGITAL IN/OUT Control Bus Data Line. 9 SCL DIGITAL INPUT Control Bus Clock Line. Charger Adapter Current Sense Positive terminal. Use a 10 mW sense resistor RAC. Bypass ACSP with a 10 mF capacitor Reverse Blocking FET Driver. Drives the gate of the RBFET NMOS Can also drive gate optional ACFET NMOS. Current based indication of system power. Amplified version of the adapter power, the battery power or sum of both. 10 TS ANALOG INPUT Battery Presence Detection. Connect this pin to the battery thermistor sensor. 11 VBAT ANALOG IN/OUT Battery Connection. Bypass with at least 10 mF capacitor. 12 BATDRV ANALOG OUTPUT 13 BCSN ANALOG INPUT Battery Current Sense Negative Terminal. Use a 10 mW sense resistor RBC. 14 BCSP ANALOG INPUT Battery Current Sense Positive Terminal. Use a 10 mW sense resistor RBC. 15 LSDRV ANALOG OUTPUT Low Side Switch Driver. Drives the gate of the DC to DC low side NMOS. 16 VCORE ANALOG OUTPUT Core Voltage. Do not connect load on this pin. Bypass with a 2.2 mF capacitor 17 CBOOT ANALOG IN/OUT 18 SW ANALOG OUTPUT Switching Node. Connection to the 2.2 mH inductor. 19 HSDRV ANALOG OUTPUT High Side Switch Driver. Drives the gate of the DC to DC high side NMOS. Supplied from the bootstrap capacitor. 20 ACSN ANALOG INPUT − EXPOSE PAD GROUND Battery FET Driver. Bootstrap Capacitor Connection. Charger Adapter Current Sense Negative terminal. Use a 10 mW sense resistor RAC. Internally connected to ground www.onsemi.com 3 NCP1871 Table 2. MAXIMUM RATINGS Rating Symbol Value Unit VIN , RBDRV (Note 1) VMR_AC −0.3 to +30 V ACSP, ACSN, HSDRV, SW, CBOOT, BCSP, BCSN, BATDRV, VBAT (Note 1) VMR_ACS −0.3 to +30 V TS (Note 1) VMR_DRP −0.3 to +7.0 V VMR_CBOOT −0.3 to +7.0 V VMR_LV −0.3 to +7.0 V VDG IDG −0.3 to +7.0 V 20 V mA Human Body Model (HBM) ESD Rating are (Note 2) ESD HBM 1500 V Charged Device Model (CDM) ESD Rating are (Note 2) ESD CDM 750 CBOOT with respect to SW (JEDEC standard JESD22−A108) LSDRV, VCORE, PRHOTB, PMO, VINOK, VSEL (Note 1) Digital Input: SCL, SDA (Note 1) Input Voltage Input Current Latch up Current (Note 3): All Digital pins( VDG) VINOK, VSEL All others pins. V ILU mA ±10 ±30 ±100 Storage Temperature Range Maximum Junction Temperature (Note 4) Moisture Sensitivity (Note 5) TSTG −65 to + 150 °C TJ −40 to + TSD °C MSL Level 1 Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product performance may not be indicated by the Electrical Characteristics if operated under different conditions. 1. With Respect to GND. According to JEDEC standard JESD22−A108. 2. This device series contains ESD protection and passes the following tests:. Human Body Model (HBM) ±1.5 kV per JEDEC standard: JESD22−A114. Charged Device Model (CDM) ±750 V per JEDEC standard: JESD22−C101. 3. Latch up Current Maximum Rating: ±100 mA or per ±10 mA JEDEC standard: JESD78 class II. 4. A thermal shutdown protection avoids irreversible damage on the device due to power dissipation. 5. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J−STD−020. Table 3. OPERATING CONDITION Symbol Parameter Conditions Min Typ Max Unit VIN Operational Power Supply 4.5 VINOV V VDG Digital input voltage level 0 5.5 V TA ISINK Ambient Temperature Range −40 25 VINOK sink current +85 °C 10 mA mF CIN Decoupling input capacitor RIN Damping resistor 2 W CAC Decoupling Switcher capacitor 10 mF CBOOT Bootstrap capacitor 100 nF CCORE Decoupling core supply capacitor 2.2 mF Decoupling system capacitor 47 mF Switcher Inductor 2.2 mH Current sense resistor 10 mW N−channel MOSFET VGS = 5 V 10 mW 10 nC (Notes 4 and 6) 50 °C/W COUT1, COUT2 LX RAC, RBC RDSONQRB, RDSONQHS, RDSON QLS, RDSONQB RDSON resistance CGQRB,CGQHS, CGQLS, CGQB Total Gate Charge RqJA TJ 4.7 Thermal Resistance Junction to Air Junction Temperature Range −40 25 +125 °C 6. The RqJA is dependent on the PCB heat dissipation. Board used to drive this data was a 2s2p JEDEC PCB standard. Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond the Recommended Operating Ranges limits may affect device reliability. www.onsemi.com 4 NCP1871 Table 4. ELECTRICAL CHARACTERISTICS Min & Max Limits apply for TA between −20°C to +85°C and TJ up to + 125°C for VIN between 4.5 V to 22 V (Unless otherwise noted). Typical values are referenced to TA = + 25°C and VIN = 12 V (Unless otherwise noted). Parameter Symbol Conditions Min Typ Max 3.5 3.8 Unit INPUT VOLTAGE VINDET Presence input detection threshold VIN rising 3.2 Hysteresis VINSYS Charger mode detection threshold voltage VINLO 175 VIN – VBCSP, VIN rising 95 150 200 mV VIN – VBCSP, VIN falling 10 50 90 mV 1.188 1.2 1.212 V VSEL rising Hysteresis 25 50 75 mV VSEL rising 0.4 0.45 0.5 V VIN rising, Ratio of VSYSMIN 103.4 106 108.6 % Hysteresis 101.4 104 106.6 % 22 22.5 23 VCELL Cells detection threshold VINMINOK Operating charger valid threshold Valid input high threshold VIN rising (Note 7) Hysteresis VINOV TVINOV Max Hot Plug Rise time V mV 50 mV V Hysteresis 125 mV ACFET present, from 0 to 30 V, no overvoltage on ACSP 10 V/ms RBFET only, from 0 to 30 V, no overvoltage on BCSP 10 INPUT CURRENT LIMITING IINLIM Input current limit Input Current Limit Range, Average value. Short Circuit Detect TINSHORT Short Circuit Detect Delay mA 3328 mA Input Current Granularity 128 mA 128 mA to 2048 mA −64 +64 mA 2048 mA to 4096 mA −3 +3 % Current Ramping IINSHORT 8064 Input Current Limit Default. (Note 8) Input Current Accuracy TIIN 128 128/16 Input Current Limit ILIM 10 11 mA/ms 12 A ms 10 BATTERY AND SYSTEM VOLTAGE VCHG Output voltage range Programmable 3328 Default value, (Note 9) Voltage regulation accuracy Constant voltage mode, ICHG>=500 mA Programmable granularity VBUCKOV System OVP VBCSP Rising mV VSYSMIN + VSYSOFF −0.5 0.5 % 16 mV 64/16 mV/ms VCHG ≤ 9V 10.8 V 9 V ≤ VCHG ≤ 13.5 V 14.4 V VCHG > 13.5 V Voltage Ramping VSYSOV 18080 21.6 V SYSOV Release Threshold Hysteresis, Ratio of VCHG Rising Edge 102 % Buck Out of Regulation VBCSP Rising, Ratio of VCHG Rising Edge 104 % BUCKOV Release Threshold Hysteresis 102 % 7. 19 V and 14.5 V versions are available upon request 8. 2560 mA versions is available upon request 9. 5.6 V, 12.352 V and 16.592 V versions are available upon request 10. 512 mA, 1024 mA and 2048 mA versions are available upon request 11. 256 mA, 128 mA and 0 mA versions are available upon request 12. 5.6 V, 5.7 V, 5.8 V versions are available upon request www.onsemi.com 5 NCP1871 Table 4. ELECTRICAL CHARACTERISTICS Min & Max Limits apply for TA between −20°C to +85°C and TJ up to + 125°C for VIN between 4.5 V to 22 V (Unless otherwise noted). Typical values are referenced to TA = + 25°C and VIN = 12 V (Unless otherwise noted). Symbol Parameter Conditions Min Typ Max Unit 17792 mV BATTERY AND SYSTEM VOLTAGE VSYSMIN Minimum System Voltage Range Minimum System Voltage Default 3328 RCELL = 0 W (2−3 cells) 7936 mV RCELL = 220 kW (3−4 cells) 12032 mV 50 mV 128 mV SYSOFF_SEL = 0, Default 384 mV SYSOFF_SEL = 1 256 mV Hysteresis Minimum System Voltage Granularity VSYSOFF System Voltage Regulation Offset CHARGE CURRENT ICHG Charge current range Programmable 128 Default value, (Note 10) Charge current accuracy 128 mA to 2048 mA −64 2048 mA to 8064 mA −3 I2C Programmable granularity TICHG Current Ramping IEOC End of Charge Current Range 8064 128 mA +64 3 128 End of Charge Current Default −64 mA mA 128 End of Charge Current Accuracy % mA/ms 1024 256 End of Charge Current Granularity mA mA 128/16 128 mA mA +64 mA REVERSE BLOCKING FET TRBDR RBDRV Rise Time 3 nC Load 2 ms TRBDF RBDRV Fall Time 10 nC Load 1 ms RRBDL RBDRV Output High Referred to ground Referred to VIN, VIN ≥ 9 V RRBDH VRBDL RBDRV Output Low VRBDH 4.45 5 30 V 5.5 V VIN < VACSP, Referred to VIN 0 V VIN > VACSP, Referred to ACSP 0 V VINOK PIN VOL IINOKLK FLAG output low voltage IVINOK = 3 mA 0.4 V Off−state leakage VVINOK = 5 V 1 mA mV BATTERY MOSFET FET and PRECHARGE MODE VPRERED Precharge Current Reduction Range SYSOFF_SEL = 0, BCSP−VSYSMIN, IBAT(DC) = 0 A. 49 399 VPRESTOP Precharge Current Reduction Range BCSP−VSYSMIN, IBAT(AC) = 0 A. 0 128 VDRCON Battery FET Reconnect Detection Threshold End of Charge, VBAT−BCSP VDOPEN Battery FET Re−open Detection Threshold Supplement, VBAT−BCSP 7. 19 V and 14.5 V versions are available upon request 8. 2560 mA versions is available upon request 9. 5.6 V, 12.352 V and 16.592 V versions are available upon request 10. 512 mA, 1024 mA and 2048 mA versions are available upon request 11. 256 mA, 128 mA and 0 mA versions are available upon request 12. 5.6 V, 5.7 V, 5.8 V versions are available upon request www.onsemi.com 6 256 −1 mV +5 mV NCP1871 Table 4. ELECTRICAL CHARACTERISTICS Min & Max Limits apply for TA between −20°C to +85°C and TJ up to + 125°C for VIN between 4.5 V to 22 V (Unless otherwise noted). Typical values are referenced to TA = + 25°C and VIN = 12 V (Unless otherwise noted). Symbol Parameter Conditions Min Typ Max Unit BATTERY MOSFET FET and PRECHARGE MODE VPRE Precharge voltage threshold VBAT rising, Ratio of VSYSMIN Accuracy 100 −2 Hysteresis IPREMAX % 512 mA 98 Precharge Current Range Precharge Current Default % +2 128 Default value (Note 11) Precharge Current Accuracy % 512 −64 VBFH BATDRV Output High VBAT ≥ 3.3 V, Referred to VBAT 4.5 VBFL BATDRV Output Low Referred to GND −0.3 TFBF BATDRV Fall Time From VBFH to VBFL, 10 nC Load TFBR BATDRV Rise Time mA +64 mA 5 8 V 0 0.3 V 200 ms From VBFL to VBFH 3 nC Load, From End of Charge to Supplement mode 2 ms From VBFL to VBFH, 3 nC Load. 5 ms I2C/SMBus FSCL Bus operating frequency 10 400 kHz TI2CTO Bus Timeout 25 35 ms VI2CINT Peak voltage at SCL line 2.7 5.5 V VI2CIL SCL, SDA low input voltage −0.5 0.5 V VI2CIH SCL, SDA high input voltage 1.7 5.5 V VI2COL SDA low output voltage 0 0.4 V 600 1200 kHz Sink 3 mA BUCK CONVERTER FSWCHG Switching Frequency Range Switching Frequency Default 800 Switching Frequency Granularity 200 Switching Frequency Accuracy FSWSMB Spread Spectrum Modulation Bandwidth FSWSMR Spread Spectrum Modulation Rate IOUTMAX Output Current Capability IPKMAX kHz −10 Ratio of FSW kHz +10 6 % 23 kHz 8 Maximum peak inductor current % A 9 A GENERAL PARAMETERS IOFF IQLB ISTBY OFF Mode quiescent current (Measured on BAT) Drop Detection Quiescent Current (Measured on BAT) PMO block quiescent current (Measured on BAT) PMO_EN = 0, VDROOP_EN = 0, VIN = 0 V, 2~3 Cells 10 PMO_EN = 0, VDROOP_EN = 0, VIN = 0 V, 4 Cells 12 OFF mode. PMO_EN = 0, VDROOP_EN = 1 VIN = 0 V, VBAT> VLOBAT, VDRP_SEL ! = 00, 2~3 Cells 80 OFF mode. PMO_EN = 0, VDROOP_EN = 1 VIN =0V, VBAT> VLOBAT,VDRP_SEL ! = 00, 4 Cells 140 OFF mode. PMO_EN = 1, VDROOP_EN = 0 VIN = 0 V, VBAT> 4 V 1500 7. 19 V and 14.5 V versions are available upon request 8. 2560 mA versions is available upon request 9. 5.6 V, 12.352 V and 16.592 V versions are available upon request 10. 512 mA, 1024 mA and 2048 mA versions are available upon request 11. 256 mA, 128 mA and 0 mA versions are available upon request 12. 5.6 V, 5.7 V, 5.8 V versions are available upon request www.onsemi.com 7 mA mA mA NCP1871 Table 4. ELECTRICAL CHARACTERISTICS Min & Max Limits apply for TA between −20°C to +85°C and TJ up to + 125°C for VIN between 4.5 V to 22 V (Unless otherwise noted). Typical values are referenced to TA = + 25°C and VIN = 12 V (Unless otherwise noted). Symbol Parameter Conditions Min Typ Max Unit GENERAL PARAMETERS EECO NCP1871 Efficiency With Recommended operating condition, VIN = 12 V , VBAT = 8.4 V, PMO_EN = 0, VDROOP_EN = 0 ECO_MODE = 1, 20 mA load 80 % VCORE Core supply voltage VIN > 5.5 V 5 V VUVLO System UVLO VIN or VBAT rising, SMBus register available TSD 4 V 135 °C GBC_SEL = 0, Default 0.2 mA/mV GBC_SEL = 1 0.4 mA/mV 2 mA/V 0.2 mA/mV 2 mA/V GAIN_SEL = 0, Default 250 kA/A2 GAIN_SEL = 1 500 kA/A2 Power Monitor Output Current Full Scale 100 mA Power Monitor Accuracy per channel 1.00x Full Scale −5 5 % 0.10x Full Scale −8.5 8.5 % 0.03x Full Scale −20 Thermal Shutdown CURRENT AND POWER MONITORING GBC Battery Current Sense Gain ABC Battery Voltage Sense Scaling GAC Adapter Current Sense Gain AAC Adapter Voltage Sense Scaling KAC, KBC IPMO IPAC,IPBC FPMO VDRPREF Mixer Gain Power Monitor Bandwidth VDRP Fast Comparator Reference Voltage DRP_SEL = 00, Relative to VSYSMIN 97 % DRP_SEL = 01 5.6 V DRP_SEL = 10, Default 5.8 V DRP_SEL = 11 6 −2.1 VLOBAT_REG = 00, Ratio of VDRPREF OFF % VLOBAT_REG = 01 105 107.5 VLOBAT_REG = 11 ILBSK PRHOTB Sink Capability Pulse Stretch Duration VBAT_RMV Battery Removal Detection Threshold 128 Output 0.4 V ms 40 mA 10 ms BATRMV_SEL = 0, Default 2.7 2.85 3 BATRMV_SEL = 1 1.5 1.6 1.7 Battery Removal Detection time IBAT_RMV 110 VDRP Slow Comparator Debounce TLBPS % ms VLOBAT_REG = 10, Default TLBDEB V +2.1 2 VDRP Fast Comparator Debounce VDRP Slow Comparator Detection Level % kHz VDRP Fast Comparator Accuracy VLOBAT 20 8 ms 4 TS Input Leakage 100 7. 19 V and 14.5 V versions are available upon request 8. 2560 mA versions is available upon request 9. 5.6 V, 12.352 V and 16.592 V versions are available upon request 10. 512 mA, 1024 mA and 2048 mA versions are available upon request 11. 256 mA, 128 mA and 0 mA versions are available upon request 12. 5.6 V, 5.7 V, 5.8 V versions are available upon request www.onsemi.com 8 V nA NCP1871 Charging Process INCHG_OK = (INOK and not VINOK_SEL) or (INMINOK and VINOK_SEL) SYS RST STATES (HW_RST & RST_TMR) or (BAT_DIS & INDET) UVLO HW_RST OFF CONFIG −Core OFF (10μA) −DCDC OFF −SMBus available −BATFET ON −RBFET OFF INDET or HW_RST −Core = OFF (BAT_DIS) −Core = ON (HW_RST) −DCDC OFF −SMBus available −BATFET OFF −RBFET OFF −Core ON −DCDC OFF −SMBus available −BATFET ON −RBFET OFF (not INDET ) & (not BAT _DIS) STBY STATES INSYS and not SYSOV and not SYSOV_INT and not IINSHORT_INT and not INOVP (HW_RST and RST_TMR) or (BAT_DIS & RST_TMR & not INDET) not INSYS or SYSOV or IINSHORT or INOVP CHARGE STATES HOLD TSD or CHR_DIS or WD_TMR or not INCHG_OK −Core ON −DCDC OFF −SMBus available −BATFET ON −RBFET ON TSD or CHR_DIS or WD_TMR or not INCHG_OK 10ms timer and INCHG_OK and not ldo_mode & not PRE & not (SYSOV TSD or CHR_DIS or WD_tmr) and not LEARN 10 ms timer and INCHG_OK and (ldo_mode or PRE) and not (SYSOV TSD or CHR_DIS or WD_tmr) PRE CHARGE FULL CHARGE PRE −Core ON −DCDC ON −SMBus available −BATFET: PRECHARGE −RBFET ON not PRE and not ldo_mode −Core ON −DCDC ON −SMBus available −BATFET ON −RBFET ON EOC or (IEOC and IEOC_EN) SUPPLEMENT −Core ON −DCDC ON −SMBus available −BATFET ON −RBFET ON not EOC and not IEOC_EN or LEARN END OF CHARGE DRCON DOPEN and not LEARN ACTIVE CHARGE STATES Figure 3. Charging State Machine www.onsemi.com 9 −Core ON −DCDC ON −SMBus available −BATFET OFF −RBFET ON NCP1871 Block Diagram RBDRV VIN ACSP ACSN HSDRV VCORE INPUT VOLTAGE VIN INDET − Amp + INSYS − + + REVERSE BLOCKING FET INSHORT VBUCKREG VCHG , VSYSMIN + VSYSOFF − + BUCKOK − VCHG x VBUCKOV CELL − HSS + INOK − VINLO QC_DRV VIIN V BUCKREG QCELL VIBAT V REF − + + + SYSOV − VSYSOV BATTERY AND SYSTEM VOLTAGE LSS CHARGE CURRENT − V IBAT BUCK CONVERTER BAT_RMV + VBAT VIN + DOPEN − VDOPEN VBAT Ideal diode VCORE VDRPREF VIPREMAX EN VIBAT Charge Pump Amp IREF POR + CLOCK VLOBAT Current, Voltage, and Clock Reference − − V PRERED VREF BATDRV TSD ACSN BCSN − VIEOC VBCSP VCORE Amp + IEOC VBAT _RMV TS + PWM generator VSEL − VCELL 22k VBAT Amp + INPUT CURRENT LIMIT + BCSP VIINSHOR T − VIIN INMINOK VSYSMIN x − VINMINOK VINSYS BUCK CONVERTER INOVP Drv LSS + − + VINOV − V BCSP HSS Drv Charge Pump + VINDET Drv + LSDRV SW CBOOT Drv ACSP ON/OFF VBAT GAC A AC EN SMD Digital & registers KAC PRE Enable on POR PMO DRCON IPBC GBC BCSP + BCSP − + VDRCON SDA CHARGER CONTROL EN A BC SMB Physical Interface I@C / SMBUS PRHOTB + V SYSMIN − IPAC KBC VBAT BATTERY MOSFET AND PRECHARGE MODE SCL BCSN ACOK_DRV Pulse Generator POWER MONITORING VINOK & INT GND Figure 4. Detailed Block Diagram www.onsemi.com 10 VINOK NCP1871 SMBUS Registers Map SMBUS slave address (binary): b0001001x. ChargeOption Register − Memory Location : 12h Bit Type Reset Name RST Value Function 0 RW POR, TR_OFF CHR_DIS 0 Charge is suspend when set 1 1 RW POR, TR_OFF EOC 0 Set 1 will jump to End of Charge state from FULL charge: signal dictated by the Fuel Gauge 2 RW POR, TR_OFF IEOC_EN 0 Set 1 enable the charger end of charge detection 3 RW POR, TR_OFF LEARN 0 Set 1 enable the LEARN mode 4 RW POR, TR_OFF PMOBAT_EN 0 Set 1 enable the Battery Power monitoring circuitry 5 RW POR, TR_OFF PMOAC_EN 0 Set 1 enable the Input Power monitoring circuitry 6 RW POR, TR_OFF GAIN_SEL 0 Multiplier Gain selection 0: Full scale 100 W 1: Full scale 50 W 7 RW POR, TR_OFF PMO_IMO_SEL 0 0 : PMO selected 1: IMO selected 8 RW POR, TR_OFF GBC_SEL 0 0: Battery Current Sense Gain is 10 1: Battery Current Sense Gain is 20 9 RW POR, TR_OFF WDTMR_SET[0] 1 10 RW POR, TR_OFF WDTMR_SET[1] 0 Watchdog timer [1:0]: 00: Disable 01: 32s 10: 64s 11: 128s 11 RW POR, TR_OFF FREQ_SEL[0] 01 12 RW POR, TR_OFF FREQ_SEL[1] DCDC frequency selection[1:0]: 00: 600 kHz 01: 800 kHz 10: 1000 kHz 11: 1200 kHz 13 RW POR, TR_OFF VLOBAT_REG[0] 0 14 RW POR, TR_OFF VLOBAT_REG[1] 1 Ratio of VDRPREF[1:0]: 00: Off 01: 105% 10: 107.5% 11: 110% 15 RW POR, TR_OFF VDROOP_EN 0 0: Critical Voltage Monitoring disable 1: Critical Voltage Monitoring enable ChargeCurrent Register − Memory Location : 14h Bit Type Reset Name RST Value 0 RW POR, TR_OFF IPRE_0 11 1 RW POR, TR_OFF IPRE_1 2 R Not Used 3 R Not Used 4 R Not Used 5 R Not Used 6 R 7 RW POR, TR_OFF ICHG_0 8 RW POR, TR_OFF ICHG_1 9 RW POR, TR_OFF ICHG_2 10 RW POR, TR_OFF ICHG_3 Function 00: 0 mA 01: 128 mA 10: 256 mA 11: 512 mA Not Used 000001 000001 : 128 mA (Lower Clamp) 111111: 8064 mA (Higher Clamp) Step : 128 mA 11 RW POR, TR_OFF ICHG_4 12 RW POR, TR_OFF ICHG_5 13 R Not Used 14 R Not Used 15 R Not Used www.onsemi.com 11 NCP1871 ChargeVoltage Register − Memory Location : 15h Bit Type Reset Name RST Value 0 R Not Used 1 R Not Used 2 R Not Used 3 R Not Used 4 RW POR, TR_OFF VCHG_0 5 RW POR, TR_OFF VCHG_1 6 RW POR, TR_OFF VCHG_2 7 RW POR, TR_OFF VCHG_3 8 RW POR, TR_OFF VCHG_4 9 RW POR, TR_OFF VCHG_5 10 RW POR, TR_OFF VCHG_6 11 RW POR, TR_OFF VCHG_7 12 RW POR, TR_OFF VCHG_8 13 RW POR, TR_OFF VCHG_9 14 RW POR, TR_OFF VCHG_10 15 R Bit Type Reset Name RST Value Function 0 RW POR, TR_OFF HW_RST 0 Set 1 will disconnect the battery after RST_TMR 1 RW POR, TR_OFF BAT_DIS 0 Set 1 disconnect the battery when IN unplug until the next IN plug 2 RW POR, TR_OFF FAULT_MSK 0 Set 1 Mask fault interuption 3 RW POR, TR_OFF STATUS_MSK 0 Set 1 Mask Status interruption 4 R STATE[0] 5 R STATE[1] 6 R STATE[2] 7 RW POR, TR_OFF RST_TMR_SET[0] 0 8 RW POR, TR_OFF RST_TMR_SET[1] 1 9 RW POR, TR_OFF FREQ_S_EN 0 Frequency Spread Spectrum enable 0: Disable 1: Enable 10 RW POR, TR_OFF CPEXIT_EN 0 0: CP exit disable 1: CP exit Enable 11 RW POR, TR_OFF IEOC[0] 1 12 RW POR, TR_OFF IEOC[1] 0 13 RW POR, TR_OFF IEOC[2] 0 000: 128 mA 001: 256 mA 010: 384 mA 011: 512 mA 100: 640 mA 101: 768 mA 110: 896 mA 111: 1024 mA 14 RW POR, TR_OFF LDO_MODE 0 Set 1 select LDO mode 15 RW POR, TR_OFF ECO_MODE 1 0: No Eco Mode 1: Eco Mode VSYSMIN + VSYSOFF Function 00000000000 : 3.328 V 00011010000 : 3.328 V (Lower Clamp) 10001101010 : 18.080 V (Higher Clamp) 11111111111 : 18.080 V Step : 16 mV Not Used ChargeOption2 Register − Memory Location : 3Ch Charge state [2:0]: 000: OFF 001: CONFIG 010: HOLD 011: PRECHARGE 100: FULLCHARGE 101: SUPPLEMENT 110: END OF CHARGE 111: HW_RST www.onsemi.com 12 Reset Timer 00: 0 ms 01: 512 ms 10: 1024 ms 11: 2048 ms NCP1871 Interrupt Register − Memory Location : 3Dh Bit Type Reset Name RST Value Function 0 RC POR, OFF EOC_INT 0 Flag End of Charge State is reached 1 RC POR, OFF PRE_INT 0 Flag Precharge state is reached 2 RC POR, OFF LEARNB_INT 0 Flag entering/exiting Learn mode 3 RC POR, OFF WDOG_INT 0 Flag a WatchDog Timer expired 4 RC POR, OFF IPEAK_INT 0 Flag IPEAK MAX is reached 5 RC POR, OFF INOVP_INT 0 Flag VIN> VINOV 6 RC POR, OFF BUCK_OVP_INT 0 Flag BUCK OV 7 R POR, OFF IINSHORT_INT 0 Flag IIN> IINSHORT 8 RC POR HW_RST_INT 0 Flag HW_RST state and HW_RST=1 9 RC POR BAT_DIS_INT 0 Flag HW_RST state and BAT_DIS=1 10 W1C POR, OFF SYSOV_INT 0 Flag System Overvoltage 11 RC POR, OFF BAT_RMV_INT 0 Flag battery is removed 12 R Not Used 13 R Not Used 14 R Not Used 15 R Not Used Bit Type Reset Name RST Value 0 RW POR, TR_OFF VDYNPRE_EN 1 0: Dynamic precharge disable 1: Dynamic precharge enable 1 RW POR, TR_OFF VINOK_SEL 0 Control VINOK signal 0: INOK is set by VSEL 1 INOK is set by VSYSMIN 2 R Not Used 3 R Not Used 4 R Not Used 5 R Not Used 6 R Not Used 7 RW POR, TR_OFF VSYSMIN_0 8 RW POR, TR_OFF VSYSMIN_1 9 RW POR, TR_OFF VSYSMIN_2 10 RW POR, TR_OFF VSYSMIN_3 11 RW POR, TR_OFF VSYSMIN_4 12 RW POR, TR_OFF VSYSMIN_5 13 RW POR, TR_OFF VSYSMIN_6 14 RW POR, TR_OFF VSYSMIN_7 15 RW POR, TR_OFF N_CELL_EN MinSysVoltage Register − Memory Location : 3Eh See electrical characteristics 1 Function 00000000 : 3.328 V 00011010 : 3.328 V (Lower Clamp) 10001011 : 17.792 V (Higher Clamp) 11111111 : 17.792 V Step : 128 mV 0: VSYSMIN default value detection disable 1: VSYSMIN default value detection enable Reset Legend: • • • • • OFF: Set bit to RST VALUE when the charging state machine is in OFF state. TR_OFF: Set bit to RST VALUE when the charging state machine transits to OFF state. POR: Set bit to RST VALUE on power on reset. W1C : Need to write 1 to reset this bit to 0 RC : Read this bit to reset to 0 www.onsemi.com 13 NCP1871 InputCurrent Register − Memory Location : 3Fh Bit Type Reset Name RST Value 0 R Not Used 1 R Not Used 2 R Not Used 3 R Not Used 4 R Not Used 5 R Not Used 6 R Not Used 7 RW POR, TR_OFF IINLIM_0 8 RW POR, TR_OFF IINLIM_1 9 RW POR, TR_OFF IINLIM_2 10 RW POR, TR_OFF IINLIM_3 11 RW POR, TR_OFF IINLIM_4 12 RW POR, TR_OFF IINLIM_5 13 R Not Used 14 R Not Used 15 R Not Used Bit Type Reset Name RST Value 0 RW POR, TR_OFF SYSOFF_SEL 0 VSYS offset selection: 0 : 384 mV 1 : 256 mV 1 RW POR, TR_OFF DRP_SEL[0] 10 2 RW POR, TR_OFF DRP_SEL[1] VDROOP threshold selection: 00 : 97% Relative to VSYSMIN 01 : 5.6 V 10 : 5.8 V 11 : 6 V 3 RW POR, TR_OFF BATRMV_SEL 0 Battery removal threshold selection: 0 : 2.85 V 1 : 1.6 V 4 R Not Used 5 R Not Used 6 R Not Used 7 R Not Used 8 R Not Used 011010 Function 000000: 128 mA 000001 : 128 mA (Lower Clamp) 111111 : 8064 mA Step : 128 mA ChargeOption3 Register − Memory Location : 40h Function 9 R Not Used 10 R Not Used 11 R Not Used 12 R Not Used 13 R Not Used 14 R Not Used 15 R Not Used www.onsemi.com 14 NCP1871 ManufacturerID Register − Memory Location : FEh Bit Type Reset Name RST Value 0 R 1 R MAN_ID[15:0] 0 0 2 R 0 3 R 0 4 R 0 5 R 0 6 R 0 7 R 0 8 R 0 9 R 0 10 R 0 11 R 0 12 R 0 13 R 1 14 R 1 15 R 1 Bit Type 0 R 1 R 0 2 R 0 3 R 0 4 R 0 5 R 0 6 R 0 7 R 0 8 R 0 9 R 0 10 R 0 11 R 0 12 R 0 13 R 1 14 R 1 15 R 1 Function DeviceID Register − Memory Location : FFh Reset Name RST Value DEV_ID[15:0] 0 www.onsemi.com 15 Function NCP1871 FUNCTIONAL DESCRIPTION Overview system supply voltage, hence the name Narrow Voltage DC (NVDC), and improves efficiency of the core converters. The device includes a voltage droop monitor, charger adapter validation and blocking as well as an intelligent battery connection control. The adapter current, charge current and system current are closely monitored and an image is provided to the host. The NCP1871 is fully programmable through an I2C compatible SMBus interface. In below figure, the block diagram of the NCP1871 in its typical application is shown. The NCP1871 is part of On Semiconductor’s growing switching battery charger family for wireless and mobile computing. The NCP1871 is a NVDC switching battery charger with characteristics that makes it perfectly suited for 2−stacked battery cell applications such as ultrabooks or tablets. The NCP1871 is designed around a full NMOS DC to DC controller that brings down the high voltage charger adapter voltage to a regulated system supply that is in the same range as the battery pack voltage. This limits the variation on the ACFET RBFET HSS RAC AC/DC 2.2uH VIN RSEL Damping network Adapter Detection 10uF RBDRV Input FET Control ACSP ACSN Adapter Detection & Cell Select SCL PBC PRHOTB PMO LSDRV Battery Current & Power Sense Charger Control RBC BCSN Precharge Control Power and Droop Monitor BATDRV Battery FET Control VIN VBAT GND BATFET VBAT VCORE 2.2uF LSS BCSP SMBus PAC Application Output Stage Drivers DC−DC Controller SDA Host 47uF 100nF SW CBOOT Adapter Current & Power Sense VSEL VINOK HSDRV NCP1871 NVDC Battery Charger Core Supply TS 10uF Figure 5. Functional Block Diagram input current as well as the battery charge current. The latter is measured by means of a low impedance sense resistor. The battery pack is connected to the system through a low impedance NMOS. This battery FET is opened in case the battery is depleted while the DC to DC directly supplies the application using the system voltage as its feedback. When charging, the battery FET is closed and the charge current is monitored. The battery voltage is used as the feedback voltage for the DC to DC. When the battery is fully charged to End of Charge state, the battery FET is opened to preserve its charge but will assist the system in case it draws more peak power than the charge adapter can deliver. The DC to DC converter runs in fixed frequency PWM mode with pulse skipping capabilities. To reduce EMI issues, the switching frequency is selectable and a frequency The charger adapter is connected to the application through a reverse blocking FET that avoids the leakage from the battery to input. The FET is made conducting when a valid charger is detected. At the same time a signal is generated to inform the host. Overvoltage detection will reject high voltage charge sources while protecting the application by blocking the high side FET of the DC to DC converter. The adapter current is measured by means of a low impedance sense resistor. This information is used by the DC to DC converter to limit the average input current. Optionally, a second FET can be placed back−to−back in series with the reverse blocking FET to provide additional isolation towards the application. The DC to DC converter supplies both the application and charges the battery pack. It regulates its output voltage, the www.onsemi.com 16 NCP1871 CORE spreading feature can be enabled which can reduce peak amplitude of the EMI energy by 10 dB. Soft start of both output voltage and output current moderate the inrush current. The DC to DC converter uses external NMOS switches to handle the high currents involved. the NCP1871 has the capability to deliver up to 8 A. Though optimized for 2−stacked cell battery packs the NCP1871 also supports 3 and 4−stacked cell batteries. Additional features include a voltage drop monitor that can supervise critical system voltage, a learn mode that allows to cycle a battery pack to re−initiate the battery pack’s fuel gauge, and a system power monitor providing a true analog image of the system power to the host. The NCP1871 is controllable through a SMBus interface that is also compatible with a 400 kHz I2C control. A sideband interrupt signal informs the system of any event occurring. The bus allows reading out the device status as well as programming the different voltage and current levels and operating modes. The NCP1871 comes in a small 3.5 x 3.5 mm QFN−20 package at 0.5 mm pitch. The IC core is supplied from a locally generated VCORE. The VCORE is a regulated supply that automatically takes the highest of the AC adapter input VIN and the battery connection VBAT as its input. The core includes a bandgap and generates all necessary references for the circuit. VCORE requires a bypass capacitor. The core operates in two distinct modes: Off and Active. In Off mode only imprecise detectors are active monitoring the VIN pin and SMBus activity while keeping the battery pack connected to the system. All other circuitries are disabled. When a VIN or SMBus activity is detected, the core transitions to the active mode where the entire core is active including the precise bandgap and clocking. In active mode the different functions of the IC can be enabled such as the DCDC converter or power monitors. The core does not operate for voltages below the under voltage lockout threshold (VUVLO) and all internal circuitry, both analog and digital, is held in reset. VIN VSYS VBAT ISYS IBAT IIN Figure 6. Typical Charge Profile www.onsemi.com 17 OFF END OF CHARGE SUPPLEMENT END OF CHARGE FULL CHARGE PRE CHARGE HOLD CONFIG OFF Charge Profile NCP1871 Pre Charge the battery will supplement the remainder of the current to avoid further drop. Once the system current is reduced below the adapter current, the system voltage will again rise above the battery voltage and the FET is opened. The battery will not get recharged in the process as long as the charger is not re−enabled through SMBus. In case of a depleted battery, attaching a valid charger will enable the DC to DC and the output voltage will be raised to VCHG. The feedback of the DC to DC converter is taken from BCSP. The battery FET will be used in a linear mode to precharge the battery pack at a current IPRE. Once the battery voltage reaches the minimum system operating voltage VSYSMIN, the battery FET is slowly turned on and the feedback is now taken from VBAT. Note that VSYSMIN is to be programmed to a value lower than VCHG. When precharging the battery, the voltage at BCSP is permanently monitored. When the output drops towards the VSYSMIN level, the precharge current is reduced to zero in an analog fashion starting with BCSP being VPRERED above the VSYSMIN level. The precharge current will drop to zero immediately if BCSP drops across VPRESTOP above the VSYSMIN level. The above described precharge behavior is the default. By opting for a LDO_MODE option, the precharge phase will be skipped. This should only be done if the battery pack can handle a safe precharge on its own. DCDC Converter The DC to DC converter uses external NMOS pass devices for both the low side and the high side switches. To drive the gate of the high side switch at HSDRV, a bootstrap capacitor is used that is connected between SW and CBOOT. This capacitor is precharged from the VCORE reference. The gate of the low side switch is directly driven at LSDRV. Not the drain of the high side switch, but the hot side of the sense resistor should be considered as the input of the converter and therefore a capacitor has to be placed at ACSP. To avoid too high ripple in the application, the capacitor is to be grounded to the source of the low side switch before connecting to the system ground. The output voltage of the DC to DC converter is regulated to the level VCHG as set in the ChargeVoltage register. Depending on the state of the battery FET the voltage at pin BCSP (FET open) or the voltage at pin VBAT (FET closed) is taken as the feedback voltage. The latter is done to avoid any early charge current reduction due to the IR drop between BCSP and VBAT. Apart from the output voltage regulation, the DC to DC converter control loop will also limit the amount of input power from the AC adapter and the amount of current provided to the battery. In other words, the DC to DC converter will only be at the set output voltage if the current limits are not hit. The input current limit is set in the InputCurrent register, the charge current in the ChargeCurrent register. Note that when the input current limit is reached, the output voltage will drop automatically thus reducing the amount of current provided to the battery. In other words, priority is given to the system current over the battery charge current. When enabled, the reference for the DC to DC output voltage is smoothly ramped. Once the output voltage ramp has finished, the charge current is ramped up. When reprogramming an established output voltage to a higher or lower value, the voltage ramp is also applied. The combination of these mechanisms limits the peak inrush current at startup and during the transitions after SMBus programming. Once enabled, the converter operates in a fixed frequency PWM mode and will pulse skip automatically when needed. The switching frequency is selectable over a small range, it is however not advised to apply ‘on the fly’ changes but to use a device instance with a different default value. During specific mode, the power consumption of the whole system is intended to be very low. An Eco mode can be enabled through I2C, (bit ECO_MODE, register ChargeOption2) which increases the efficiency at very light load (10−20 mA). Full Charge In case of an already connected battery, attaching a valid charger will enable the DC to DC with VBAT as the feedback voltage. If at the end of the voltage ramp the VBAT is greater than VSYSMIN, the battery FET remains closed and full charging is engaged. For VBAT below the VSYSMIN however, the battery FET is automatically made non−conducting, the pin BCSP taken as the feedback, and the battery pack pre−charged as described above. By this overlapped approach the system will remain correctly supplied when opening the battery FET. End of Charge Once the battery is fully charged the battery FET is made non−conducting. This avoids wear and tear of the battery cells and enhances the battery pack’s lifetime. The fully charged state is determined by the battery pack’s fuel gauge. Through SMBus the battery charger is then disabled. This does not mean that the DC to DC converter is disabled, just that the battery is no longer charged. Normally, it was still being charged with a small current before disabling charging for a full battery, so after the battery FET is opened, the system voltage is slightly above the battery voltage. The end of charge detection by the charger is not the preferred method; termination by the fuel gauge is preferred at large due to the correlation between end of charge and 100% battery capacity. However, the end of charge detection may be helpful as an additional means of protection. The end of charge detection should therefore be set low. Upon an end of charge detection an interrupt is generated. Supplement Mode With the FET non−conducting, the system current may exceed the power rating of the wall charger. As a result the system voltage will drop. When a significant BCSP drop of VDRCON is detected, the battery FET will be turned on and www.onsemi.com 18 NCP1871 the LC resonance created on the switch node. In absence of prolonged switching activity, the bootstrap capacitor will discharge. In order to maintain the capacitor charge, the low side FET will be turned on periodically so that the bootstrap capacitor can be recharged again to VCORE level. To protect the DC to DC converter output transistors as well as the inductor, a peak current limiter will limit the cycle to cycle peak current. It uses the voltage drop over the input current sense resistor to monitor the peak current. A flag bit is set to inform the host about the event but the DC to DC converter is not automatically disabled. This particular skip mode is active when the input current is lower than 100 mA. If so, the TONMIN is extended to reduce switching activity and frequency as a consequence. The buck also regulates in asynchronous mode. As soon as ECO_MODE is set to ‘0’ whatever the input current is, the eco mode is disabled. The DC to DC converter switches at fairly significant current levels which could cause conducted and radiated EMI issues. A frequency spreading option can be enabled to reduce the side−effects of this. By varying the switching frequency at a constant low rate (i.e. a modulation with a triangular waveform), the peak amplitude of the EMI energy in the output spectrum can be reduced by about 10 dB. Note that the amount of power itself is not reduced, just its allocation over the frequency band. When pulse skipping, the current in the inductor will fall to zero for each cycle (discontinuous operation). At that point both the low side and high side switches are non−conducting, and the SW node will be ringing caused by Current and Power Monitoring The current and power monitoring block consists of an analog output signal reflecting the amount of power taken by the system and an open drain output signaling the host that excessive power is drawn by the system. The below diagram depicts the power monitoring functionality. IPAC = KAC ( AAC*VAC * GAC*VIAC ) ACSP IPBC = KBC ( ABC*VBC * GBC*VIBC ) AAC VAC KAC VIAC VBC GBC VIBC BCSN KBC IPAC IPBC G AC ACSN ABC IPMO = IPAC + IPBC BCSP RPMO Figure 7. Power Monitoring Diagram to the PMO output. The current measurement signal is also used by the DC to DC converter to limit the input currents and by the adapter over current protection circuitry. The current flowing out of and into the battery is sensed through the sense resistor RBC connected between the pins BCSP and BCSN. The measurement is low pass filtered to remove any current spikes due to the transient load response of the system. The resulting signal is multiplied with the battery voltage at BCSN and amplified to the PMO output. The current measurement signal is also used by the DC to DC converter to control the charge current. The battery power sense circuitry can be enabled in both charging and non charging modes. In order to inform the Host about the amount of power used by the system, an image of the power taken from the charger input and the battery pack is provided at the power monitor output PMO. PMO does take into account the power that is sourced to the battery during the charge cycle. Based on this information, the host can determine if it is reaching the maximum power level it is allowed to take from either source. The adapter current is sensed through the sense resistor RAC connected between the pins ACSP and ACSN. The measurement is low pass filtered to remove the current ripple due to the DC to DC activity. The resulting signal is multiplied with the adapter voltage at ACSP and amplified www.onsemi.com 19 NCP1871 VOLTAGE DROOP MONITOR The below diagram depicts the voltage monitoring functionality. BCSP BAT _RMV VDRPREF VLOBAT INSYS PRHOTB PRHOTB_DRV IINLIM_DISABLE & CPEXIT_EN 1 shot Pulse Stretcher (TPS ms ) Figure 8. Critical Voltage Monitor Diagram Input Current Limitation The critical system voltage node, is connected to BCSP and is monitored for a sudden drop due to high loading conditions. A comparator with a programmable threshold is used for this. This comparator is enable when bit VDROOP_EN is set to 1 (register ChargeOption). For additional adjustment, the detection level can be adjusted with VDRP_SEL bit of ChargeOption3 register. This comparator can be disabled under low battery conditions to avoid false triggering (bits VLOBAT_REG, register ChargeOption). The overall system can be enabled in both charging and non charging modes. Note that under low battery conditions the processor peak current will be automatically reduced by the system so that critical voltage droops are avoided. The output of the drop monitor is fed into a pulse stretcher that will ensure the PRHOTB pin will be pulled low for a guaranteed minimum period TPS which will reduce the processor speed (PROCHOT# pin) and thus the power consumed. BAT_RMV and INSYS signal leads to a PRHOTB generation as well. Apart from the output voltage regulation, the DC to DC converter control loop will also limit the amount of input power from the AC adapter and the amount of current provided to the battery. In other words, the DC to DC converter will only be at the set output voltage if the current limits are not hit. The input current limit is set in the InputCurrent register. Note that when the input current limit is reached, the output voltage will drop thus automatically reducing the amount of current provided to the battery. Battery FET The battery pack is connected to the system voltage rail through the NMOS battery FET (BATFET), driven from BATDRV. In order to support all operating modes of the application, the battery FET can be operated in three states; fully conducting, non−conducting and linear mode. When the application is in off mode and no charger is attached, the system voltage is maintained by the battery. The BATFET is fully conducting by BATDRV being driven high through a charge pump to VBAT plus VPUMP. The charge pump features a very low bias current when maintaining BATDRV high. This current is accounted for in the core quiescent current. When the application is operating without any charger attached, the battery FET is by default fully conducting when the VBAT is greater than the undervoltage threshold UVLO while non−conducting for lower voltages (fully depleted battery). Watchdog Timer Description The battery charging cycle is under control of the host. It may happen that the host is too busy to survey the charger or that the system is stuck. As a safety measure therefore a watchdog timer is started after each I2C write in charge current or/and voltage setting registers during active charge states. When the watchdog timer is enabled, the charge will be suspended if IC does not receive any write charge voltage or write charge current command within the watchdog time period. This timer can be set or disabled through SMBus registers. www.onsemi.com 20 NCP1871 Adapter Detection and Removal VINOK Output The AC adapter is connected to the input VIN which is permanently monitored by a set of comparators. A first imprecise low current comparator will detect the presence of an input voltage greater than VINDET. This comparator is always enabled even when the core of the circuit is in off mode. Once detected, the more precise input voltage detectors are enabled. The precise voltage detectors will validate if the applied charger is in the proper input range bounded by VINLO (on VSEL pin) and VINOV(on VIN pin) or VINMINOK depending on VINOK_SEL (see SMBUS Registers Map). To guarantee a robust detection, debounce timers are added to the VINLO detection. The VINOV acts as an overvoltage protection that rejects too high voltage chargers in order to avoid damage to the application. When the input voltage is valid (VSEL > VINLO and VIN < VINOV) or (VINMINOK < VIN < VINOV) depending on VINOK_SEL bit (register MinSysVoltage), the open drain VINOK pin is released and pulled high by the external pull up resistor thus signaling the host that a valid supply is attached. When becoming invalid the opposite applies. The SMBus doesn’t has a slave interrupt feature. To inform the host about an event a sideband signal is to be used. On the NCP1871 the VINOK pin flags to the host when a valid charger is attached. Given the non critical timing of the VINOK signal for this use case, an interrupt is signaled as a short ‘not VINOK’ pulse. The short period of the pulse allows distinguishing an interrupt from a charger removal. An interrupt can only be generated when a valid charger is attached. The interrupt feature can be enabled and disabled through the control bus (Bit FAULT_MSK and STATUS_MSK, Register ChargeOption2). Register Interrupt inform the system about the nature of interruption. I2C Signal Nature Flagged on VINOK Associated Mask Bit EOC_INT RC Dual Edge Yes STATUS_MSK 0: Not in End of Charge state 1: End of charge state PRE_INT RC Dual Edge Yes STATUS_MSK 0: Not in Precharge State 1: Precharge state LEARNB_INT RC Dual Edge Yes STATUS_MSK 1: Enter/Exit Learn Mode WDOG_INT RC Single Edge Yes STATUS_MSK 1: Wd timer expired Description IPEAK_INT RC Single Edge Yes FAULT_MSK 1: IPKMAX reached. INOVP_INT RC Dual Edge Yes FAULT_MSK 0: INOVP = 0 1: INOVP = 1 BUCK_OVP_INT RC Dual Edge Yes FAULT_MSK 0: BUCKOV = 0 1: BUCKOV = 1 SYSOV_INT Write 1 to Clear Yes FAULT_MSK 1: SYSOV HW_RST_INT RC Single Edge No NA 1: HW_RST state and HW_RST=1 1: HW_RST state and BAT_DIS=1 BAT_DIS_INT RC Single Edge No NA INSHORT_INT No Clear Yes FAULT_MSK BAT_RMV_INT RC Single Edge Yes STATUS_MSK 1: INSHORT = 1 0: Battery is present 1: Battery is removed Battery Removal Event occurs A battery removal pin TS can be used to monitor battery presence. This allows the charger to anticipate a potential voltage drop of the system rail in case of battery removal. If a battery is suddenly removed, a PRHOTB is immediately generated, informing the system that the battery is no longer available for supplement. If this event appears during learn mode, the buck is immediately forced to VCHG. The PRHOTB length is 10 ms allowing enough time for the system to take into account this event, and adapt its power management accordingly. 200us VINOK Valid Adapter Attached Figure 9. Interrupt Signaling www.onsemi.com 21 NCP1871 VSYSMIN Default Value Detection limited to the capacitor at ACSP. It is therefore thought that a back to back configuration of a reverse blocking FET RBFET with an input FET ACFET is not necessarily required, By using a back to back FET configuration however, the charger can be isolated from the application thus providing additional protection against system short circuits and overvoltages. A back to back FET combination also allows connecting some additional charging related circuitry just right after the input FETs while taking advantage of the overvoltage protection. When a system short circuit occurs that exceeds the input and peak to peak current limits, the RBDRV pin will be made low and the charger will have to be removed to unlatch this condition. When exceeding the system overvoltage threshold VSYSOV, SYSOV_INT bit will be triggered as system over voltage, need to Write 1 to Clear this bit and release this protection. For effective isolation the ACFET will have to be added to create a back to back configuration with the RBFET. Both mechanisms add additional safety in case the DC to DC converter does not manage to limit the voltage or current due to for instance a shorted high side switch or other malfunctioning. User can select the VSYSMIN default value thanks to an external resistor RCELL. The resistance should be put in series with VSEL pin as follows: 2 /3 Cells configuration V IN 3 /4 Cells configuration V IN R2 R2 V SEL V SEL RCELL R1 R1 Figure 10. Resistor Network for CELL Detection RCELL must be 220 kW if 3/4 cells config selected. R1 is also fixed to 22 kW, and R2 is used to select VINOK threshold. The following table illustrates VINOK versus R2. Learn Mode The NCP1871 provides a special battery learning cycle that helps to calibrate the battery fuel gauge. This cycle is performed while an adapter is attached. Upon the SMBus LEARN command the DC to DC converter is immediately forced to VSYSMIN+VSYSOFF, so the application would be supplied from the battery therefore discharging the latter. When LEARN is finished (normally by fuel gauge) or battery is removed, the charge can resume normally. Constant Power Exit In case a PRHOTB generation is not sufficient to stop the voltage drop during a very strong load transient, some AC adapters are designed to provide more power than their nominal value. In that case, the charger must disable the input current limit to allow full power to flow through it. This mode is enabled thanks to CPEXIT_EN bit in register ChargeOption2. If this bit is set to 1, the input current limit will immediately be disabled during PRHOTB generation. As soon as PRHOTB disappears, the input current limit is enabled again. Figure 11. VINOK versus R2 Table This function can be defeated through I2C (bit N_CELL_EN, register MinSysVoltage). Upfront Protection To avoid the battery voltage supplying the AC adapter input pin, a reverse blocking element is required. One could use a Schottky diode but given the high current levels in play, the dissipation would be excessively high and overall efficiency degraded. This is resolved by using a reverse blocking FET (RBFET) function that simulates an ideal diode. The RBFET is an NMOS type and its gate driven from RBDRV. An internal charge pump will provide a RBDRV drive voltage of VIN plus VCORE. When attaching a charger, the DC to DC converter is not yet operational and the system is isolated from the charger by the DC to DC converter high side switch. Therefore, upon attachment the capacitive loading seen from the battery charger through the body diode of the RBFET remains AC Adapter Overvoltage Protection In case of an overvoltage, the DC to DC converter is immediately disabled and the RBDRV pin made low, so a−synchronously with the core logic. The converter and RBDRV are enabled again when the overvoltage condition disappears. The converter is definitely disabled by the core logic and the charger rejected when the overvoltage condition persists. When connecting an AC adapter, transient voltages greater than the maximum ratings of the IC can occur. Appropriate filtering will have to be placed upfront to stay below these levels. www.onsemi.com 22 NCP1871 Hard System Reset For SMBus the SDA and SCL logic low and high levels are defined as absolute voltages, where they are relative to the supply for I2C. Although specification wise this may lead to conflicting situations, in practice this does not cause an issue when operating from 3 V and 5 V supply rails. The interface of the NCP1871 uses absolute levels and is supplied by the bus lines itself. For SMBus the clock frequency is within 10 kHz and 100 kHz where I2C allows for 0 Hz while in the widespread fast mode it can run up to 400 kHz. The minimum clock frequency for SMBus allows for implementing a bus timeout mechanism. When the master keeps the bus clock low the slave will release the data lines and the transaction is aborted (equivalent to an I2C STOP command). Limiting the clock frequency of the interface to the SMBus standard could lead to conflicts on an I2C bus. The NCP1871 therefore supports up to 400 kHz. This has no side effects on the SMBus operation itself. Note that the bus clocking is independent from the core logic clocking. For SMBus a slave should always ACK its device address but is allowed to NACK after any of the data bytes. On I2C one is allowed to NACK the address. The NCP1871 will actually never respond with a NACK and therefore always provide an ACK. A smart battery charger on a SMBus has an imposed bus address of 0001001b. Optionally, the NCP1871 includes a different I2C address (available upon request). The smart battery charger protocol imposes a word (low byte, high byte) write/read protocol with one address per 2 bytes. In I2C, the single byte write/read is more common where each byte of data has its own individual address. However, most I2C masters can perform an auto increment to perform a 2 bytes consecutive write/read starting with the low byte, also see the appendix. The diagram below summarizes this. A hard system reset is initiated after the user has pressed the power button for a long period, usually 8 seconds. The keyboard controller can then through SMBus program the system reset bit after which the BATDRV pin is temporarily made low to GND and the system reset bit cleared. To totally isolate the battery pack from application, back to back configuration of BATFET will be needed. Upon HW_RST bit is set to 1, a RST_TMR timer is launched and BATFETs are made non conducting when this timer is expired. This RST_TMR timer ensures the system can turn off correctly after HW_RST bit is set 1. The Timer also determines the BATFET OFF duration. Battery Disconnect In web tablets and ultrabooks, the battery pack is embedded and is shipped while being partially charged. To avoid the battery getting slowly discharged by the application while being on the shelf, the battery pack is totally isolated from the application by adding a second MOS in a back to back configuration. By setting the battery disconnect bit through SMBus, after a delay of RST_TMR, the BATDRV pin will be made low to GND when the adapter is removed and will be kept low as long as the battery power remains available. To exit this state a valid charger will have to be inserted which will reconnect the battery pack and reset the disconnect bit. Serial Interface (SMBUS) The device is widely programmable through the SMBus interface. The SMBus is based on the I2C interface with some exceptions. These exceptions are documented in the SMBus specification 2.0 that is available at smbus.org. The I2C specification is available from the NXP website or through i2c−bus.org. The SMBus implementation on the NVDC charger is I2C friendly allowing it to be used on non SMBus applications. The most noticeable differences between the two standards to the NVDC charger are listed below. www.onsemi.com 23 NCP1871 Application Information Typical Application Negative Protection circuitry QNP R1 Damping Network QAC AC ADAPTOR R2 QRB RIN QHS C2 C1 CIN LX QLS RAC CBOOT COUT1 COUT2 SYSTEM LOAD DF CAC RI1 RBDRV VIN VDD R3 D1 RCELL ACSP ACSN HSDRV SW CBOOT LSDRV BCSP VSEL RBC RI2 BCSN BATDRV VINOK SDA HOST NCP1871 QBAT SCL VBAT RTS PRHOTB TS PMO VCORE RPMO GND CCORE RUP 10k BATTERY PACK CBAT +5V Figure 12. Additional Circuitry for Negative Protection Table 5. BILL OF MATERIAL Reference Description Manufacturer / Part Number Value 4.7 mF / 50 V CIN Decoupling input capacitor RIN Damping Resistor 2 W / 0.5 W CAC Decoupling Switcher capacitor 10 mF / 50 V CBOOT Bootstrap capacitor 100 nF / 25 V CCORE Decoupling core supply capacitor 2.2 mF / 6.3 V COUT1, COUT2 Decoupling system capacitor 47 mF / 25 V CBAT Decoupling battery capacitor DF Clamping Schottky Diode LX Switcher Inductor RAC, RBC QAC, QRB, QHS, QLS, QBAT 10 mF / 50 V MBRM120E / ONSEMI IHLP−2525CZ−01 / VISHAY Current sense resistor 20 V / 1 A 2.2 mH / 8 A 10 mW / 1 W Power MOSFET N−channel NTTFS4C10N / ONSEMI RTS Battery Hotplug Current Limit Resistor RUP Battery Removal Pull Up resistor 10 mW / 30 V 1 kW / 0.1 W 100 kW / 0.1 W R1 QRB Reverse protection biasing resistor 3.01 MW / 0.25 W R2 QRB Reverse protection biasing resistor 1 MW / 0.25 W R3 RBDRV Reverse protection resistor 4 kW / 0.5 W Power Monitor Resistor 33 kW / 0.1 W C1 Reverse protection capacitor 2.2 nF / 50 V C2 Reverse protection capacitor 0.1 mF / 50 V RPMO QNP D1 Reverse protection NMOS Schottky Barrier Rectifier RI1, RI2 Minimum input voltage valid resistor RCELL Number of cell selection resistor www.onsemi.com 24 2N7002L / ONSEMI 7.5 W / 60 V MBRA340T3G / ONSEMI 3 A / 40 V See VSYSMIN Default Value Detection NCP1871 Input Damping Network charger circuitry by blocking the negative voltage and R3 limits the current flowing into the ESD protection circuitry thus avoiding damage. C1 and C2 ensure the VGS of QRB and QAC remains 0 V during negative hot plug. A Damping network is recommended in order to avoid voltage ringing on the input. On the following example (see Figure 13) with a 1 mH / 0.1 W cable, the maximum input voltage is higher than 30 V and can damage the application. In Figure 14, a damping network 1 mF / 2 W is added so the input voltage is smoothed to 22−24 V maximum. Components Selection Inductor Selection Inductor electrical selection depends on maximum current, frequency and duty cycle. The saturation and DC current are defined by: I SAT + I CHG ) 0.5 I RIPPLE The inductor ripple current depends on input voltage (VIN), duty cycle (D = VOUT /VIN), switching frequency (FSWCHG) and inductance (LX): I RIPPLE + ǒV IN D ǒFSWCHG (1 * D)Ǔ L XǓ The maximum inductor ripple current happens for D = 0.5 IRIPPLE = VIN / (4 x FSWCHG x LX) So maximum current is given by ISAT = ICHG + 0.5 x VIN / (4 x FSWCHG x LX) Please note that the NCP1871 switching frequency is selectable. Figure 13. Hot Plug Behavior without Damping Network Power MOSFETs Selection NCP1871 is designed to drive N−Chanel MOSFET with 5 V gate drive voltage and an operating voltage up to 24 V. Due to voltage transient, a 30 V N−MOSFET is preferred. QAC, QRB, QHS, QLS and QBAT are all N−Chanel MOSFET and can be identical. It is also recommended to select a very low RDSON MOSFET (10 mW typically for VGS = 4.5 V) with a total gate charge around 10 nC typically. NTTFS4C10N from ON SEMICONDUCTOR is the perfect fit with NCP1871. For QBAT, one more thing needs mention: since BATDRV would be pulled low to GND during shipping mode or hard system reset action, which means VGS at this time would be (–VBAT), the NFET needs to be selected with enough VGS rating especially for 3 or 4 cells application. Figure 14. Hot Plug Behavior with Damping Network Input Negative Protection A negative voltage protection on input is defined by the negative protection circuitry (see Figure 12). In normal operation, QNP is off (VGS < 0 V). D1 is conducting and R1, C1 and C2 have no continuous effect. When adapter voltage is reversed, QNP VGS is positive causing QNP to turn on. As a consequence, the source and gate node of QRB is shorted so QRB is off and the battery side circuitry is protected by the body diode of QRB. At the same time, D1 is protecting input PCB Layout Recommendation Proper layout of the components is recommended in order to minimize high frequency current path loop and to prevent high frequency resonant problems and electrical magnetic field radiation. www.onsemi.com 25 NCP1871 GND PLANE CIN COUT CAC QLS LX RIN AC ADAPTOR QAC VIN QRB RBDRV RAC ACSP ACSN HSDRV RBC CBOOT QHS SYSTEM LOAD QBAT BATTERY PACK CBOOT SW LSDRV BCSP SENSE DC POWER BCSN BATDRV NCP1871 VBAT AC POWER TS VCORE SUPPLY & DRIVER CCORE GND Figure 15. Typical Layout Recommendation • CCORE Capacitor must be placed as close as possible to It is crucial to take the following rules into account. • The switching loop (AC power track) composed by CAC, RAC, QHS, QLS, LX, COUT must be as short as possible and placed on the same layer of PCB. This track must be isolated from GND plane, only COUT cold node is connected to the GND plane. This track must be large enough to reduce impedance of track (8 A typ). • The impedance of DC power track composed by QAC, QRB, RBC and QBAT must be as low as possible and placed on the same PCB layer as the AC power track. This track also must be large enough (8 A typ). • • the IC and routed on the same PCB layer as the IC. The connection to GND (expose pad) should be short and connected to COUT cold node with a unique track. Use Kelvin connection for RAC and RBC sensing and do not route these sense leads through a high di/dt or dv/dt path. Supply and driver track must be large enough (1 A max). LSDRV and HSDRV are switching nodes; track must be shortened to reduce parasitic inductance. www.onsemi.com 26 NCP1871 PACKAGE DIMENSIONS QFN20 3.5x3.5, 0.5P CASE 485CP ISSUE O PIN ONE REFERENCE ÇÇÇÇ ÇÇÇÇ ÇÇÇÇ ÇÇÇÇ B A D NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M, 1994. 2. CONTROLLING DIMENSION: MILLIMETERS. 3. DIMENSION b APPLIES TO PLATED TERMINAL AND IS MEASURED BETWEEN 0.15 AND 0.30 MM FROM TERMINAL TIP. 4. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS. L L L1 DETAIL A E ALTERNATE TERMINAL CONSTRUCTIONS DIM A A1 A3 b D D2 E E2 e K L L1 0.10 C 0.10 C ÉÉÉ ÇÇÇ EXPOSED Cu TOP VIEW A 0.05 C A3 MOLD CMPD A3 ÇÇÇ ÉÉÉ A1 DETAIL B MILLIMETERS MIN MAX 0.80 1.00 −−− 0.05 0.20 REF 0.20 0.30 3.50 BSC 2.10 2.30 3.50 BSC 2.10 2.30 0.50 BSC 0.30 REF 0.25 0.45 0.00 0.15 ALTERNATE CONSTRUCTIONS 0.05 C DETAIL B NOTE 4 A1 SIDE VIEW C SEATING PLANE RECOMMENDED MOUNTING FOOTPRINT 0.10 C A B DETAIL A D2 3.80 2.36 K 6 20X 0.57 0.10 C A B 20X 11 L 1 E2 2.36 3.80 1 16 e BOTTOM VIEW 20X b 0.10 C A B 0.05 C PACKAGE OUTLINE 20X 0.50 PITCH NOTE 3 0.35 DIMENSIONS: MILLIMETERS ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. 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